Electronic discharge tube control



Patented Dec. 12, 1950 UNITED STATES PATENT orncag George A. Bonadio, Watertown, N. Y.

Application October 22, 1949, Serial No.'123,074

Claims. (Cl. 250-275) This invention re ates to electronic discharge apparatus of the type wherein a foraminous electrode is utilized to control the passage of electrons through the apertures. More particularly, this invention relates to a new and improved structure for a grid electrode for thermionic type tubes or valves.

One purpose of this invention is to afford more eflicient control of an electronic valve.

Another purpose of this invention is to provide a control electrode which will act upon an electron stream in a more uniform fashion than the type of control electrode which has been hitherto almost universally employed.

Still another purpose of this invention is to provide an electronic valve incorporating therein a control element, the characteristics imparted by which to the valve, when employed as an amplifier, are such that the non-linear distortion effects are of a nature diametrically opposed to the effects found in valves employing the customary type of control grid.

A still further purpose of this invention, which derives from the last mentioned purpose, is to provide an amplifying valve which may be cascaded with conventional amplifying valves, so that the distortion effects of the two types of valves will tend to mutually cancel one another, thereby yielding substantially distortionless amplification. v

Fig. 1 shows, in front elevation and highly magnified, a single elemental portion of a conventional grid.

Fig. 2 shows, also in front elevation, a single element of the control electrode of the present invention.

Fig. 3 is a side elevation, in cross section, of the control electrode of Fig. 2, as combined with the other electrodes of a valve.

Fig. 4 is a front elevation of a multiple element grid, constructed according to the present invention.

Fig. 5 shows a family of curves of a conventional electronic tube.

Fig. 6 shows a family of curves of the tube of this invention.

Referring now to Fig. 1, the vertical rods I and 2 are the supporting members for the grid proper, which latter has here indicated two cross wires 3 and 4, these being welded or otherwise fastened to the supporting rod. The dotted rectangles 5, 6 and I represent equipotential fields of force. Since the effect exerted upon an electron by the usually negative charge upon the grid is related to the distance of the electron from the grid, it can readily be seen that an electron passing through the grid at a point lying along the innermost rectangle 1, would be affected by the charge upon the grid Wires- 3 and tion, in order that the grid efiects may be more uniform. However, this type of grid gives rise to the well known general type of grid poten tial/anode current, shown in Fig. 5. Y

Reference is now made to Fig. 2, wherein the control electrode efiectively takes the form of a pointed member 8 situated in the center of an aperture 9 located in a metallic plate III. In this case, the lines of force, indicated at II and [2, are entirely symmetrical and an electron stream passing therethrough will be of a generally circular cross section.

Referring now to Fig. 3, the elements of Fig. 2 are there shown as assembled relative to a cathode l3 and an anode M. The metal plate I0 is connected to the grounded cathode, so that the full potential existing between the control grid 8 and the plate 10, will be at a maximum. The anode is shown schematically, and may be of any convenient type.

Reference is now made to Fig. 4, wherein is shown a metallic plate l5 having therein a plurality of apertures 9, in the center of each of which is located a control grid 8. If this multiple plate be employed with a suitably shaped cathode, there will efiectively be produced a plurality of circular electron streams, passing through the control plate. It is to be understood that such multiple element control 8190? trode may take on any configuration suitable to the cathode and anode with which it is employed, and this invention is not limited to a flat plate type control electrode.

Referring now to Fig. 6, there is here illustrated the general type of amplification curve produced by an electronic tube employing a control grid according to the invention here disclosed. It will be noted that this family of curves have'nonlinear distorting characteristics in the opposite direction from the curves shown in Fig. 5. It will therefore be evident that if a convention-a1 type tube be cascaded, or otherwise connected, with a tube according to this invention, the distortion effects of the two tubes will tend to cancel out,

r I 3 thereby yielding an over-all amplification curve which will be substantially linear.

A still more practical method of securing this same cancellation of distortion is by utilizing both types of control grid within a single envelope, i. e as portions of a single tube structure.

While I have shown and described certain embodiments of this invention, it is to be understood that many changes of detail, especially as to the relative size and shape of the constituent element, may be made without departure from the spirit of the invention, a defined in th following claims. I

Having now shown and described my invention, what I particularly claim and desire to secure by Letters Patent of the United States of America is as follows:

1. An electronic valve of the pure electron discharge type and having as functioning elements at least a cathode, an anode and a control electrode, characterized in that said control electrode comprises a. metallic shield provided with at least one substantially circular aperture therein, and a relatively small and substantially pointed control member proper located substantially in the center of said aperture, but insulated from said metallic-shield, said metallic shield bein positioned adjacent the cathode, and being metallically connected thereto, so as to be equipotentia therewith.

2. A grid'control electrode according to claim 1-, in. which said metallic shield is provided with disposed therethrough, each aperture being provided with a centrally located pointed control member.

3. In an electronic valve, a control element located between the cathode and the anode of said valve, comprising a forarninous grounded metallic plate, having in the center of each aperture thereof a pointed control member proper, insulated from said plate.

4. A structure according to claim 3, in which said apertures are substantially circular and said pointed control members are located substana plurality of circular apertures, symmetrically tially in the center of the respective apertures.

5. An electronic valve of the vacuum type and including therewithin a thermionic cathode, an apertured plate adjacent and electrically connected to said cathode, an anode, and a control electrode formed as a rod of relatively small diameter having the main body thereof substantially parallel to said apertured plate, having one end portion substantially perpendicular to said plate, and having the extremity thereof positioned within the aperture of said plate.

GEORGE A. BONADIO... I

Name Date Depp Apr. 10, 1945 Number 

